Algin gel-forming compositions



Patented May 18, 1948 ALGIN GEL-FORMING COIVIPOSITIONS Arnold B. Steiner, La Jolla, Calif., assignor to Kelco Company, San Diego, Calif., a corporation of Delaware No Drawing. Application December 8, 1943, Serial No. 513,643

(01. sea-131i 15 Claims.

This invention pertains to the formation of gelatinous products by the interaction of alginates with certain salts, notably the salts of calcium.

The primary purpose of the invention is to control the time required for gelatinization to .occur and the consistency of the gel so proproducts such as fruit jams and jellies, jellied A salads and broths, water jelly desserts and candy jellies. Inedible jellies may also be made for various industrial purposes, such as gels for dental impressions, lubricating and insecticidal jellies and the like.

It is well known that water-soluble alginates react with soluble calcium salts to form the insoluble calcium alginate. Under some circumstances this product is gelatinous, but the reaction is of little use for the production of jellies. The reaction is extremely rapid, cannot be controlled efiectively and ordinarily yields a product of grainy or even granular consistency.

It is also known to restrain the formation of calcium alginate by the addition to the above reactants of a bufier salt, such as one of the alkali metal phosphates. This procedure is not satisfactory for my present purpose. To produce any material extension of the setting time requires a large proportion of the bufier salt, the course of the reaction is profoundly influenced by temperature changes, and the product is loaded with mineral salts to a degree undesirable for food products.

It is also known to use as a source of calcium a slowly soluble salt such as calcium sulfate. This reaction is usually too fast to be useful for the present purpose, calls for the use of a large excess of the calcium salt, and produces only gels having a strongly alkaline reaction. In the method herein described, only a minor proportion of the calcium or other gel-forming salt is used, and the product may range from neutral to a strongly acid reaction.

I have discovered that by the use, with a soluble salt of alginic acid, of a salt (of calcium, for example) which is only very slightly ionizable or unionizable in an aqueous medium, together with a weakly acid substance or a substance which produces free acid in aqueous solution, I am enabled to produce a gel of any desired consistency and degree of acidity, from hot to cold solutions, with complete control of the setting time, and either with or without the addition of sugars. These results have not, so far as I am aware, been produced heretofore.

The materials which I use, and the ranges of equivalence so far as I presently know them, are in detail as set forth immediately below:

(1) A water-soluble algin. This may be the alginate of ammonium, magnesium, potassium, sodium or other alkali metal, or the alginate of an organic base such as mono-, dior tri-ethanolamine, aniline, etc. These soluble algins may be prepared by well known methods such as disclosed in the following United States Patents: 1,814,981, Thornley & Walsh, July 14, 1931; 2,036,922, Clark 8: Green, April '7, 1936; 2,039,934, Green, April 7, 1936; and 2,128,551, Le Gloahec, August 30, 1938.

' The viscosity of the algin is not critical, though the higher viscosity algins form stronger gels than those of lower viscosity. As the compositions are usually prepared in the dry form, the algin is comminuted. The most favorable grain size depends on the usage of the composition. Thus, when used in boiling solution, as in making candy jellies, a 40 Tyler mesh product is suitable, while for use in gels made with cold water a finer mesh is preferable as hastening solution, as for example a grain size passing a mesh screen.

(2) A salt, preferably of calcium, which either is insoluble or very slightly soluble in water, or which inaqueous solution is only slightly ionized, or both, and which on the addition of an acid yields cations which gelatinize alginates. This might otherwise be defined as an algin-gelatinizing sa-lt having a low solubility product. In still other words, the salt in an aqueous medium must not yield any material number of the cations which gelatinize the algenic component until a definite step, the addition of the acid component, is performed.

Examples are tricalcium phosphate, dicalcium phosphate, calcium sulfate, calcium oxalate and i i so i for the celciurnj salts.

metals are more OlIlGSS toxic; I v I I g Up'to this time I have obtained 'myibest re f sults; in, theusevof ,tricelclum phosphate; cal- I variousgelatinizedfood productsxi 7 I i j '(33' A weakly acidic substance: to-wit; a weak I I cium tartrate: or: calcium alglnate in; preparing:

- gelatinlze the algin by: converting it into the inl- 5 Wlube cal i I 1 1 salt, as tendingtothe production of clear gels. I I

, On the addition of a free acid the calcium salt j I v isslowly ionized to yield calcium ions, these free I I I i i i I free acid, or fasubstjance whichlibel'ates acid on I i solution in water. In'th'e list of weak: acids may {is I be named acetidjcitrlc, glutaric, lactic, succinic,

tartaricggluconic and alginic. Substances whichi yield free acldfoin solution inweterinclude, first; 1 a the acid lactones, of which d-glucono lactone is I r i an example: second, the acid or br salts ofjthei I I alkali metals with; some 'orthe organic jacids ,ias

v i f i purpose r the em i i 1 viiiu I 5 dill!!! bis: 7 v

theusje of a solid acidic substance isdesira-ble, I l

.cium salt and acid and, finally, by the {use of E v z inhibitors (ingredient #4) which are ordinarily function in ascm befpointed out he i faf fili- Ql' g or gel-retarding salt. IThe I v etarding salt (retarder) is, I I first, to repress the ionization of the g l-mam: i salt until the acidic. ingredient added and 1, I I thereafteii',v @to retarclfthe liberation of, the eel- I l forming (e .g.',calciuml cations: i j C I salts of such acids as acetic, citric. iand't I I fous phosphoric acids; ,Thesetend to, inhibit I formation by reascnof their} bulfer action, their i I v I I alkalinityi, their corrimon ion effect or a conbi nation of these effects. Ingeneral these inhibiti n t le the bitartrates of'potassium and so' assium blnoxalate and biphthalate, soihaye obtained my best results in the use. of .dgluconolacton e an-dthe acidtartraflesq I I I The free acids and the a id salts and lactones awhat difi'erent manner, as will I I I 4;) a gel-lnhi' iti ors are salts of weak acids.

Thus, for example, if trlcalcium phosphate is used to furnish the gelling calcium cations, the addition of trisodium phosphate maintains the alkalinity sufilciently high to prevent premature solution of the calcium phosphate and the common phosphate ions tend to repress ionization of the calcium salt. The use of a mixture of monobasic and dibasic sodium phosphates likewise exerts these effects and, upon addition of a relatively strong acidic ingredient, maintains through buffer action a moderate acidity which tends to permit gradual release of the calcium ions with attendant gradual setting of the calcium gel.

Particularly favorable mixtures for this purpose have been found to be (1) a mixture of Calgon (sodium hexametaphosphatel, disodium phosphate and monosodium phosphate. and (2) a mixture of Calgon with trisodium phosphate. While the hexametaphosphates of the other alkali metals are not articles of commerce at this time, there is every reason to believe that they will be functional, equally with the sodium salt, when they are obtainable.

There is much latitude in the use of these inhibitors, depending on the nature of other ingradients used and the manner in which the composition is used. In some cases the use of an inhibitor is unnecessary.

The function of each ingredient of the composition and the difierence in functionality between free acids and the substances which yield acid on solution in water should be pointed out.

{governed by the rate at whi takes place: This, in tu n; is g I herent 2 7 v r v the temperature obta lining,v and lnaujcasesthe 'solubleqalginate(ingredient, I

#13,); :i the source of :alginiand the calcium: saltv j i v ,-(#,2) the source jofvthe ;calcium;required ton uvj,

ionsimm'ediately reacting with the soluble alginate to ior m insoluble calcium ailginate. r I II I the calcium ions are removed from soIutionIin' I i I this mannen'more areliberatedandthizs gelstion'proceeds through'theigradual ionization of i v the calcium saltend the rate of a lation willbe I I ch t v onizability of the ear '11: strength and v concentration; of. the

his ionization; 1 8d 'by'the jini I isalt, on the z g acid. used, on I I on the nature I I and amount of the gel-retarding salti As the tem; f 1 i i he va'ria Z el; 1 @the rate: at which the; acid-y1eld1ng substance are and ammonlumbimalate. where I 5 i i re m i Pi lm final productto be made I required in the use of ireeaci-d; I I

will mainly be controlled I When the third ingredient is a I by the nature of the I i the speed or gelation I 03; the selection of cal: I I

bstjance which if d yieldsa id on be g placed in aqu ous s lut n.v 1 o rather than affree acid, the reactions take place I 1 I I I in three stages instea'cl of theitwo aboye described; I 'Ihef first stage is the dissociation of the acide i i p I v I yielding substance with the; gradual; liberation I of freeiacld; the second theiionizatlon of thecal- 5 N This component maybe one. or the some men i I i cium a r the i it s ee andv the rd I I I the formation of calcium alginate; In: this case I I dissociates or by the rate at which t e liberated; l v I l I acid ionizes thecalcium salt, and the selection I f of an acid-yielding body having a low dissoci atlon rate may be made the governing factor in retarding the rate of g elation.

It will be understood that in the above remarks the reference to calcium salts is intended to be illustrative only, The same principles apply in the use of the corresponding salts of the other alkali-earth metals and of the heavy metals.

The term a salt whose cations are no more than slightly liberated in water is intended to cover the type of salt above described, having a low solubility product. The desired effect of restricting the presence of free calcium or similar cations to the lowest possible terms may be realized through low solubility, or low ionizability, or more often through both of these characteristics. It is conceivable, however, that a substance might be completely ionized in water and yet furnish only a negligible number of cations, due to its extremely low solubility. On the other hand, a much more soluble substance might yield the same negligible number of cations by reason of its low inherent ionizability. It is preferred to use a substance for this purpose which has a solubility product not higher than 10- at 25 Cent.

The manipulation of these mixtures may take 5 two forms, depending on the physical condition of the acidic substance (ingredient #3) and on the temperature to which the composition is subjected after adding it to the water which makes up the bulk of the jelly.

If the acidic constituent be a solid, a lactone or bitartrate for example, and ii the jelly is to be produced in the cold way, all tour or thaeomponents may be mi'i tedin one composition which wfll then produce the desiredge] when added to water. i'ruit .luice, syrup or other aqueous liquid. This is obviously impractlcal in the use 01' acetic, lactic, orv other liquid acid. In the utilization of fruit juices, fairly heavy buii'ering may be required to prevent too rapid gelatlnizatlon. or even precipitation of calcium alglnate.

It is also diflicult, though not impossible, to handle a composition containing even a dry acidic component in cases where the composition is to be blended with a hot liquid.'as.in the making of candy jellies, by reason oi.-'the strong acceleration oi the reactions by the high temperature. For working in. the hot way, and in the use of liquid acids, we therefore prefer "to mix the soluble alginate, the calcium saltand the retarding agent (if any), to bring the mixture into aqueous solution at convenience, and to add the acidic constituent only when ready to bring about the setting reaction.

The admixture of the three or four components. as the case may be, prior to introduction to the water or aqueous liquid, is a matter of convenience only and the components may be added to the liquid separately if preferred. From the standpoint of the use, it,i s a real advantage to have as many as possible of the constituents blended in advance in the proportions in which they give the best results for some specific use or type of use. I therefore aim to produce mixtures of the four components, the utility of which is somewhat circumscribed, and mixtures of three of the components, the fourth being withheld for separate addition, useful under all conditions.

Following are examples of compositions adapted to the manufacture of edible gelatinized products by both the hot and the cold methods. All

formulae are in parts by weight.

Example L-Candy jelly-hot method Parts (1) Sodium alginate 46 (2) Tricalcium phosphate 3 (4) Monosodium phosphate parts 17 Disodium phosphate d 17 (3) d-Glucono lactone 17 Sucrose 1,800

Glucose (80% solids) 1,800

Water 2.400

Components 1--2-4 are mixed and added to the boiling water, in which the soluble components of the mixture dissolve almost immediately, in about one minute. The sugar is then added and followed by the glucose, the syrup being boiled up after each addition. The temperature of the syrup is then raised to about 221 F. and any desired coloring and flavoringing-redients added.

At this point the lactone (component #3), prevlously dissolved in a small quantity of water, is stirred into the cook-which may then be poured into suitable molds.- The'mixture remains thin enough to pour readily for about one hour after adding the lactone and setting is complete in about three hours. More rapid setting may be produced by reducing the proportion oi'component #4.

The product of this operation is a clear, smooth candy jelly which maintains an unchanged con sistency over a wide range oi -temperature. The

of sodium bitartrate for the an unsweetened gel is given below.

Example 2.--Unsweetened gel-hot method Parts (1) Sodium alginate 50.4 (2) Tricalclumphosphate 3.4

(4) Disodium phosphate parts.... 8.4

Sodium acetate -do 18.8

(3) d Glucono lactone 21.0

Water 2,600

Components 1-2-4 are mixedandstirred into the water at boiling point, dissolving in a couple of-mlnutes. The solution is boiled up and the lactone stirred in. A strong, clear gel is formed in about two hours.

It is not necessary to work with boiling water. but to hasten solution in cold water it is desirable to add a dispersing agent for the alginate, sucrose being effective for this purpose.

Eicample 3. Col d water gel Parts (1) Ammonium alginate ll (2) Tricalcium phosphate .l (3) d-Glucono lactone 85 (4) Sodium hexametaphosphate 3 Sucrose 235 Water 1,100

- Example 4.C'old water gel Parts (1) Sodium alginate 38.9 (2) Tricalcium phosphate 2.6

(4) Disodium phosphate parts 14.6 Trisodium phosphate do 14.6 Sodium hexametaphosphate do 7.3

(3) Lactic acid (50%) 22.0

Sucrose. not over 300 'Water 2,000

Components 121 4 are stirred into waterat atmospheric temperature. When solution is complete component #3- is added The magma is thin enough to pour after thirty minutes and gelation is complete in about one hour from the time the acid is added.

Example 5.Cold water gel This composition, when manipulated in the same manner as in Example 4, gives the same result as to setting time and character of gel. By increasing the dosage of sodium hexametaphosphate to 15.2 parts the setting time is approximately doubled.

The sugar may be omitted from the formulae of either Example 4 or Example if a wholly unsweetened gel is desired. Or either of these formulae may be used, in the same manner as Example l, to make a candy jelly by the hot method, using sucrose and glucose in more or less equal parts and in a total proportion such as to give a product of the desired sweetness and body.

Example 6.Hot water gel Parts (1) Sodium alginate 21.3 (2) Calcium alginate 21.3 (4) Monosodium phosphate parts 10.6 Disodium phosphate do 10.6 Sodium hexametaphosphate do 12.1

(3) Lactic acid (50%) 25.1

Sucrose 1,800 Glucose 1,800 Water 2,200

The water is brought to boiling and constituents i--2-4 added. The sugars are then dissolved and finally the acidic component (#3) added with stirring. This blend was still thin enough to pour for an hour after adding the acid and set to a firm gel in about another hour.

Example 7.-Candy gel-hot method Parts (1) Sodium alginate 57.2 (2) Calcium tartrate 3.8 (4) Trisodium phosphate parts 4.8

Sodium hexametaphosphate do 11.4

(3) Lactic acid, 75% 22.8

Sucrose 1,800 Glucose 1,800 Water 2,400

When manipulated as described in connection with Example 1 this composition sets to a very firm, clear gel in about one hour. 0n increasing the calcium tartrate to 9.5 parts a stronger gel was obtained. I

On substituting calcium sulfate (2Hz'0) for the calcium tartrate in the above formula the magma thickened at the end of about five minutes and set in about one-half hour. The set may be retarded further by increasing the proportion 0! sodium hexametaphosphate.

Example 8.-Cold water gel Parts (1) Ammonium alginate 11.6 (2) Calcium pyrophosphate 1.2 (3) d-Glucono lactone 87.2 Sucrose 230 These components are stirred into 1200 parts water at room temperature, yielding a gel of medium strength on standing over night. For the calcium pyrophosphate in the above formula, calcium sulfate (CaSO4.2H.2O), or calcium tartrate, or barium sulfate may be substituted, all yielding gels of somewhat varying strength. These are examples of gels produced without the use of a retarder.

A convenient and highly desirable method for preparing these compositions for the consumer is illustrated in the following example:

Example 9.-Processed composition Parts (1) Sodium alginate 71 (2) Tricalcium phosphate 1-; 5 (4) Trisodium phosphate parts 6 Sodium hexametaphosphate do 18 Water -300 The above components are mixed to form a water paste, which may be wet ground if desired to reduce the calcium salt to a state of extreme subdivision. The paste is then dried in thin sheets or after extrusion in threads through small orifices, after which it is granulated to pass a screen of say 40 mesh. The product of this operation is characterized by the intimate intermixture of the components, a minute part of each component being present in each granule.

The advantages of this procedure are that the solubility of the alginate is enhanced and the intimacy of dispersion of the calcium salt materially improved. A further advantage over simple mixtures of the dry powders is that the components of the processed mixture cannot stratify. This may occur in simple mixtures. by reason of the wide difference in specific gravity between the alginate and "the calcium salt.

The above composition may be used to make a candy jelly by the hot method, by adding '70 parts of the above to 2400 parts of boiling water, then adding 1800 parts each of sucrose and glucose and, finally, 30 parts 50% lactic acid or its equivalent in other acid yielding substance or acid. The details of the manipulation may be those recited in connection with Example 1.

The solubility of compositions prepared in this manner may be still further enhanced by incorporating sucrose or dextrin in the paste, and in this manner a granular product may be prepared which is almost instantly dispersible in water. This general method of preparation is not limited to the specific formula of Example 9 but may be used in connection with any of the three-component mixtures above described or any modification of them.

In preparing a processed composition, considerable manipulation may, be saved by starting with alginic acid, as in the following example:

Example 10.-Procssed composition ll]. of the above are dry weights and the water .ctually present in the wet alginic acid, together 11th any water of crystallization of the carbonate, hould be allowed for. The alginic acid, sodium arbonate and the larger part of the water are nixed to form a pasty mass, the quantity of alkali eing slightly .varied, if necessary. to bring the lydrogen ion concentration of the paste within he range pH 7.0 to pH 8.0. The mixture of odium phosphates is then dissolved in the reaainder of the water, the finely ground tricalium phosphate being added last. After thorough lending the mixture is dried and ground as bove described.

The gels produced by the general methods bove set forth are characterized by their clarity .nd firmness. They may be prepared in any delred consistency by varying the relation between he aqueous liquid and the added gelatinizing gents. Unless artificially flavored, these gels are ubstantially odorless and tasteless. As excess old is neither necessary nor harmful to the ailing reactions, the products may be practically leutral or as acid as may be desired. The prod- .cts have no tendency toward stickiness and may eadily be removed from the molds in which they .re shaped.

I claim asmy invention:

1. The method of gelatinizing an aqueous liq- :id which comprises: introducing into said liquid water-soluble salt of alginic acid, a salt whose ations form a water-insoluble salt with alginic old and which has a solubility product not subtantially exceeding at 25 0., and a wateroluble alkali metal salt of a weak acid, and addng to said liquid a weakly acidic substance only .fter the introduction of said salts and after aid water-soluble salts have passed into solution 2. A method substantially as set forth in claim in which said salt of alginic acid is sodium lginate.

3. A method substantially as set forth in claim in which said salt whose cations form a waternsoluble salt with alginic acid is tricalcium phoshate.

4. A method substantially asset forth in claim in which said alkali metal salt consists at least a part of sodium hexametaphosphate.

5. The method of gelatinizing an aqueous liqlid initially substantially free from acidity which omprises: introducing into said liquid a wateroluble salt of alginic acid, a salt whose cations cm a. water-insoluble salt with alginic acid, an .lkali metal salt of a weak acid and an acidic ubstance which liberates its hydrogen ions only lowly in contact with water.

6. A method substantially as set forth in claim in which said salt of alginic acid is sodium .lglnate.

7. A method substantially as set forth in claim in which said salt whose cations form a water-insoluble salt with alginic acid is tricalcium phosphate.

8. A method substantially as set forth in claim 5, in which said alkali metal salt consists at least in part of sodium hexametaphosphate.

9. A method substantially as set forth in claim 5, in which said acidic substance is an acid lacone.

10. A method substantially as set forth in claim 5, in which said acidic substance is di-glucono lactone.

11. The method of making a candy jelly which comprises: dissolving in water a minor proportion of an agent consisting substantially of a water-soluble alginate, a salt whose cations form a water-insoluble alginate and which has a soiubility product not to exceed 10* at 25 0., and an alkali metal salt of a weak acid; heating the solution so formed and adding a major proportion of sugar; boiling the sugar-containing solution. and gelatinizing the boiled solution by adding thereto a minor proportion of a weakly acidic substance.

12. The method of making a sugar-free gel which comprises: dispersing in hot water an agent consisting substantially of sodium alginate, tricalcium. phosphate, and an alkali metal phosphate; boiling the aqueous dispersion, and adding d-glucono lactone to the boiled liquid.

13. The method of making a cold-water gel which comprises: dispersing in water at substantially atmospheric temperature sodium alginate.

tricalcium phosphate and an alkali metal phosphate; stirring until the water-soluble components pass into solution; adding to said solution a weakly acidic substance, and maintaining the mixture at substantially atmospheric temperature until gelation occurs.

14. The method of making a cold-water gel which comprises: dissolving in cold water a finely comminuted, dry mixture of a water-soluble alginate, tricaicium phosphate, d-glucono lactone,

sodium hexametaphosphate and a dispersin agent selected from the group consisting of sucrose and dextrin, and maintaining the solution at substantially atmospheric temperature until gelation occurs.

15. An agent for geiatinizing an aqueous liquid: a comminuted, solid mixture comprising a water-soluble salt of alginic acid; a salt whose cations form a water-insoluble salt with alginic acid and which has a solubility product not exceeding 10- at 25 C.; d-glucono lactone, and a phosphate of an alkali metal.

ARNOLD B. STEINER.

REFENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 19,719 Hall Oct. 8, 1935 1,814,986 Walsh July 14, 1931 2,010,340 Williams et al. Aug. 6, 1935 2,036,922 Clark et al. Apr. 7, 1936 2,059,541 Thompson et al. Nov. 3, 1936 2,064,387 Schwartz Dec. 15, 1936 2,076,036 Leo Apr. 6, 1937 2,334,281 Olsen et al. Nov, 16, 1943 2,405,861 Tod Aug. 13, 1946 2,420,308 Gates May 13, 1947, 

